Angsheng Li Weilin Li Yicheng Pan Linqing Tang Definable Filters in the Structure of Bounded Turing Reductions. 116-124 2008 TAMC http://dx.doi.org/10.1007/978-3-540-79228-4_10 conf/tamc/2008 db/conf/tamc/tamc2008.html#LiLPT08